The present invention relates to a new and improved method and device to be used in conjunction with the diagnosis of herniated lumbar disc disease, particularly in humans.
The human spinal or vertebral column consists of a plurality of separate vertebrae, joined to each other to permit forward, backward and sideways movement of the column. At the lower end of the spinal column are the lumbar vertebrae which support the small of the back. Above the lumbar vertebrae are the thoracic vertebrae, which lie behind the thoracic or chest cavity. The uppermost cervical vertebrae define the skeletal framework of the neck. The vertebrae are separated and supported against each other by cushioning elements or discs, and are held together by ligaments. The discs are subject to deterioration and deformation, often creating significant pain.
Studies have shown that the intra-disc pressure in the lumbar spine while in a supine position is in the neighborhood of 15-25 Kpa, while pressures while in a sitting position average between 150 and 200 Kpa. These correspond roughly to pressures of 7.5 and 30 psi, respectively. The observation that patients with herniated lumbar disc disease are least comfortable in a sitting position may be at least partially due to such pressure differences.
Magnetic Resonance Imaging (MRI) techniques are often used in the diagnosis of lumbar disc disease. Experience has shown, however, that it is not uncommon to find a disassociation between the severity of a patient""s clinical symptoms and evidence of disease shown through MRI findings. The disassociation can be in part explained by the general inability of conventional MRI diagnosis systems to allow the patient to be imaged when placed into a variety of positions, including the sitting position, to vary the intra-discal pressures and alignment of the vertebrae. The supine position, in which all conventional MRIs of the lumbosacral spine are performed, is associated with the lowest intra-discal pressure, and is thus not a good position to provoke disc herniation, and is thus far from an optimal position for effective disc herniation diagnosis. It has been shown, for example, than an L5-S1 protrusion was noticeably augmented when the patient was in the sitting position.
In U.S. Pat. Nos. 6,000,399 and 5,762,073 to one of the present inventors, a method and apparatus for positioning a patient more optimally for lumbar disc disease MRI diagnosis is set forth. Such a method and apparatus requires the patient, while lying in a supine position, to be positioned between first and second force-accepting means at opposed ends of a frame with the patient""s knees slightly bent. With the patient applying muscular force to straighten the knees, and the patient""s body restrained by the force-accepting means, compression is placed on the lumbar spine. MRI imaging conducted during the force exertion allows the herniation provoked by be compression to be identified and observed.
While the aforementioned method and apparatus significantly improve the accuracy and efficiency of MRI lumbar disc disease diagnosis, such methodology and device is subject to several shortcomings. The patient may be unable to exert sufficient force for a sufficient length of time to allow a proper MRI image to be created. Alternatively, the patient, while physically able to generate sufficient pressure, may be under significant pain when such pressure is applied to prevent maintenance of the pressure. Further, while force generated by the patient can be monitored, it is often difficult to direct the patient to exert a particular amount of force to assist in associating the level of force with the degree of herniation.
It is accordingly the purpose of the present invention to provide an improved method and device for positioning a patient for the diagnosis of herniated lumbar disc disease in connection with MRI diagnosis procedures.
A further purpose of the present invention is to provide such a method and device which does not require the active participation by the patient.
Still a further purpose of the present invention is to provide such a method and device which can allow the force applied to the patient to be varied incrementally and to be continuously monitored during the application thereof.
In accordance with the foregoing and other objects and purposes, a device constructed in accordance with the present invention comprises a harness that engages the patient while lying in a supine position at a location above the lumbar spine area and a footrest against which the patient""s feet are placed. The harness is connected to a tensioning device located at the footrest. The patient lies with his or her feet against the footrest of the device and with the knees in a locked position. In accordance with the invention""s methodology, a tensioning force is applied to the harness, which is transmitted to the patient and compresses the spine, and particularly the lumbar portion thereof. With the tension and compression applied, the patient is positioned within the MRI imaging apparatus and an image is taken. The amount of compression is adjustable; indicators may be provided to provide a constant readout of the tension and thus pressure applied to the spine.